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Full text of "The Morphology And Evolution Of The Apes And Man"

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CHAPTER VIII.
THE   ORGANS  OF  DIGESTION  AND
ABSORPTION.
THE loose, thick, fleshy lips are projected over the maxillae, and in the living animal only a small part of the red margin of the lower lip is visible when the mouth is closed. Their inner surfaces are studded with the openings of numerous labial salivary glands. The labial frenula are long and narrow. The gape of the mouth is wide. The cheeks are loose and mobile, but no pouches exist. The vestibule is semilunar, and receives the secretions of Stensen's ducts, which open on papillae placed as in ilan. And a row of papillae lies beside the salivary papilla on each side in the Chimpanzee (fig. 29, C). Rex (132) described the histology of the lips, and Ehlers ^441a) described folds of mucous membrane connecting the gums and cheeks in the Gorilla. Deniker (44) believes, however, that these folds are individual variations.
The palate alters its relative dimensions as age advances (p. 121), and Keith (100) has tabulated figures showing how the length, width and area differ at birth and in the adult state in both sexes. Its mucous membrane is thrown into several rugae, in contradistinction to those in Man. The incisive papilla is frequently 14